1. Field of the Invention
The present invention relates to image display devices and, more particularly, to display panels having directional control over images being displayed.
2. Description of the Related Art
A three-dimensional (3D) visual effect is created for a viewer when the viewer's left eye sees something different than the right eye. Specifically, when a person looks at an object, the left eye forms a left-eye image IL of the object, while the right eye forms another, slightly different, right-eye image IR of the object. The differences between a left-eye image IL and a right-eye image IR can be seen by looking at an object with the left eye while the right eye is covered, and then with the right eye while the left eye is covered. Both images IL and IR are sent to the brain, which processes them in order to obtain a 3D image of the object.
Existing techniques for simulating this 3D effect have required the viewer to wear special visors, glasses, or other viewing aids. However, autostereoscopic displays have been developed to present 3D images to viewers without requiring the viewer to wear glasses or other viewing aids. Specifically, autostereoscopic displays attempt to create the 3D effect by displaying two slightly different images in slightly different directions. By displaying these different images directly to the left and right eyeballs of the viewer, the 3D effect can be established.
Various types of autostereoscopic displays are described in “Autostereoscopic Displays and Computer Graphics”, by Michael Halle, Computer Graphics, ACM SIGGRAPH, 31(2), May 1997, pp. 58-62, the entire contents of which are herein incorporated by reference. As described in this reference, existing autostereoscopic displays use optical elements such as lenses, varifocal mirrors, and lenslet arrays, to generate 3D images.
For example, one type of system relies on a lenticular sheet array to divide the viewing field into “slices” in which the 3D images can be seen. If the viewer correctly situates him/herself within a slice, different images are displayed directly toward the viewer's left and right eyes, respectively. However, the 3D effect is reduced if the viewer is not sitting within one of these slices. The positioning of these slices is dependent on the refractive qualities/dimensions of the lenslet sheet array and, thus, is not controllable by the display device.
Also, manufacturing the optical elements used in typical autostereoscopic displays poses serious problems. It is very difficult to make such optical elements (e.g., lenslet sheet arrays) with high quality and, yet, keep them affordable. This tends to limit the resolution and quality of the 3D images produced by autostereoscopic displays. For example, it is particularly hard to reduce the dimensions of lenslets in a lenticular sheet arrays, thus limiting the resolution of the 3D images produced.